Method of producing mixed coal gas and water gas



M y 1929. F. D. MARSHALL 1,

XED COAL GAS AND WATER GAS METHOD OF PRODUCING MI Filed April 10, 1926 3Sheets-Sheet INVENTOR dam M ATTORNEY May 14, 1929. F. D. MARSHALL METHODOF PRODUCING MIXED COAL GAS AND WATER GAS 7 Filed A ril 10, 1926 3Sheets-Sheet 2 di m/J y 14, 1929- F. D. MARSHALL 1,713,189

METHOD OF PRODUCING MIXED COAL GAS AND WATER GAS Filed April 10, 1926 5Sheets-Sheet 3 46) INVENTOR -A ee'0Eez /9mr m4 ATTORN EY Patented May14, 1929.

FREDERICK DEACON MARSHALL, F WEYBRIDGE, ENGLAND.

METHOD OF PRODUCING MIXED COAL GAS AND WATER GAS.

Application filed April 10, 1926. Serial No. 101,074.

This invention has reference to the art of treating carbonaceoussubstances for the production of useful by-products and, particularly,mv invention relates to a new and useful method or process of producingmixed coal-gas and water-gas.

In the course of this description, various objects and effects of myinvention will be made to appear and, to enable the same to be clearlyunderstood, I have provided drawings showing a form of apparatus bywhich my process can be commercially practiced or carried out, and insaid drawings: I

Fig. 1 is a vertical, central section of the retort structure taken online 1-1 of Fig. 3 showing a pair of top feed screws in elevation andillustratin by arrows the direction of fuel under car onization and byother arrows the upward ascent of gas. The View also shows coke in theprocess of discharge from the under end of the retort.

Fig. 2 is a transverse section of the upper feeding casing structureillustrated in Fig. 1 and shows the feed casing with a charge ofhydrocarbonaceous material, such as bituminous coal, within the casing.

Fig. 3 is a transverse section taken on the line 33 of Figure 1 throughthe retort casing proper and shows the relations of the cells forcontaining material to be carbonized, to the gas tubes or ducts.

Figs. 4 and 5 illustrate another form of the invention, Fig. 4 being avertical central section of the retort structure taken on line 44 ofFig. 7 and Fig. 5 being a vertical central section at substantiallyright angles to Fig. 4.

Fig. 6 is a transverse section of the upper feed casing and with thefuel charge in place, at line 66 of Fig. 4; and

Fig. 7 is a transverse section of the retort taken on line 77 of Fig. 4.

Fig. 8, which is a horizontal sectional view, illustrates another formof cellular retort casing proper construction and wherein material to becarbonized is shown in place in vertical cells and wherein also gasducts are shown.

Fig. 9 is a fra mentary horizontal sectional view showing the locationof the gas outlets at the upper end portions of the gas tubes.

Fig. is an elevation of a plant assemblage useful in operation ofpresent method.

Fig. 11 is an elevational plan of what is shown in Fig. 10 partly incross-section taken on the line 1010 of Fig. 10.

I do not herein claim the apparatus set forth as that forms the subjectmatter of my application Ser. No. 101,073, filed April 10, 1926, whichhas matured into Patent No. 7,704,094, and of even date herewith. Saidapparatus is also partially set forth in my application Ser. N o.101,072,'filed April 10, 1926, which has matured into Patent N 0.1,704,093.

In the accompanying drawings, 1 is the retort casing proper wherein thematerial to be gasified is contained. 2 is the head casing; 2 are a pairof non-contacting feed screws which may either overlap or receive theperipheries of the helices just clearing each other; 3 are the gas ductsshown as connected by cross webs m to the inner sides of the retortcasin g. It will be noted that these ducts have gas escape openings attheir upper end portions. Their tops are closed but they are openat-their under ends. The charge receiving cells 3 are open both at topand bottom. The cell walls are indicated by 3". All the duct orpassageway walls are connected by'webs w. The retort casing l isenclosed by a spaced apart combustion or heating chamber wall 3.

To prevent coal or other material passing down the gas ducts, the opentop of each is fitted with a cover or stopper S above the gas ductescape slots 8.

4 is the expansion joint shown in this case at the bottom end of theretort casing and formed by an annulus which encloses the lower end ofthe retort casing 1 with a space between the exterior of the casing walland the interior wall of the annulus. This space is filled with asuitable packing 4 5 is the coke receptacle which forms the frame workof balanced flap doors 6 shown attached to a rocker shaft 6, the ends ofwhich are provided with counterweights 7 for closing and maintaining thedoors in a closed position. 8 are the twin screw shafts; 9 is the gasoutlet; 10 is the inlet for fuel to be gasified; 11 are gas-tightsupporting glands from which the screws depend.

12 is the turning gear which has been specially designed for the presentpurpose and which is connectible with anelectric motor. The speed ofwhich may be stepped down to give the feed screws a rotational speed offrom 6 to 10 revolutions per hour.

The cross section for a retort 1 shown in Fig. 8 is merely another formof the cellular construction above described.

The short screws in the upper non-heated casing act as collectors of thematerial and propellers or plungers of the same to force the materialwhich is fed to these screws or ropellers downwards through the heatedbody of the retort casing proper, where the material undergoescarbonization or gasification.

The experience has been gained by the inventor to efiect low temperaturecarbonization at a temperature ranging between 900 1200 Fah. that thethickness of the material under the process of carbonizatipn orgasification must not exceed four and one-half inches and that provisionmust be made for applying this heat to all four sides of the material.

As the density of the resultant coke from the material is entirely duenot to temperature but to the expansion of the material while in asemi-carbonized or semi-plastic condition and as this expansion exerts agreat force, provision must be made that the space through which thematerial is forced by the pressure, the screws to travel are ofsufficient strength to withstand the great pressure.

The bore of the upper feeding casing and the lower carbonizing sectionis practically the same and when both are soon empty they wouldrepresent a true bore from end to end of both sections when fittedtogether.

The bore of the upper section is filled by the two screws which can beof the overlapping but non-contacting type, or the screws need notoverlap but just clear each other. I

The bore of the lower casin or retort roper is, however, cut up or su-divided in horizontal and vertical alignment by a number of radially ortransversely disposed members, but so that the spaces enclosed by thesemembers do not exceed approximately four and one-half inches at theirthickest line of diameter.

These radial and transverse members are an integral part of the retortcasing itself, being cast as part of the same, and by reason of theconductivity of cast iron and by molecular afiinity of the iron the heatapplied to the exterior of the retort is conducted through all thetransverse and radially disposed members and is so imparted to thematerial which fills the retort cells or chambers durin its passagethrough the same.

The sai cells or chambers need not necessarily be of the samecross-sectional area or shape as they may be so shaped as to produceslabs of coke, bearing always in mind the four and one-half inchescondition or they may be disposed in honeycomb form for the purpose ofproducing a briquette like form of coke.

The said members or walls forming the cells or chambers may be locatedbetween the outer casing and inner hollow tubes. These tubes are used asgas ducts for aiding the rapid withdrawal ofthe evolved gases from i theretort and have nothing to do with the heatin of the same.

' During the evolution of the gases the gas outlet is, under theinfluence of sub-atmosphenc pressure owing to the action of the gasexhauster 33, which is diagrammatically indicated.

The-evolved gases find their way to their outlet through the centres ofthe charges of material as owing to the pressure exerted on the foursides by the expansion of the charges during carbonization, very littleor no as can find its way up between the outer sides of the charges andthe inner surfaces of the containing cells or chambers.-

The tube ducts being open at each end are naturally susceptible to theexhauster suction on the interior of the retort generally, and as theevolved gases seek to leave the centres of the charges by the pathofiering the least resistance, 1t is open for these gases to leavepartly direct throughthe upper portion of the charges or partly throughthe lower ends of the gas-ducts, and the arrows in the drawing the asestake.

uch value is'attached to these ducts as the easier and with lessresistance the gases can escape, the chances of their being *cracked orsplit up is greatly lessened.

To increase the through-put capacity of the retort, the divisions in theretort may be disposed in an annular manner and provided all divisionsare connected hysically with the outer hearer periphery o? the retort,the carbonization of the interior layers will be as e%ually wellefiected as in the outer layers.

T e power exerted by the coacting screws in the upper casing on the massof material forced through the lower casing is enormous and provisionhas to be made to eject the charge of carbonized coke from the casingautomatically and continuously before the pressure on the material leadsto destructive consequences.

According to my invention this is efiected by the installation at thelower end of the casing of a coke box or receptacle within which a pairof flap doors are installed working on hinges which when in a horizontalcondition close the bottom of the superimposed casing in apracticallygas-tight manner as the edges of the flaps are bevelled to the sameangle as the tapering sides of the coke box orreceptacle against whichthey contact, so that the foot of the columns of coke in the casin reston the flaps which are kept in position y a lever attached to each flapwhich levers are controlled by weights or springs.

The desired pressure to be exerted by the coacting screws on the chargeof material to.

show the approximate paths accordingly so that when the pressure on thecharge reaches a certain point the flaps are forced open and a portionof the charge in the form of coke is ejected into the gastight box orreceptacle below the flaps. WVhen the pressure is being relieved, theWeight on the levers causes the flaps to return to a horizon-talposition.

At intervals the coke receptacle 1S opened and the coke removed duringwhich period the revolution of the eoacting screws may be stopped andthe flaps held up to ensure against the entering of air into the retortcaslng.

The design of the flaps may be varied and instead of hinging them ontheir long sides they may be hinged on their short sides in either casebeing controlled by the outside levers fitted with either weights orsprings.

The density of the coke can be varied by the amount of pressure it issubjected to during its formation in the retort and this controllablevariation of pressure is another feature of my invention.

To take up the expansion of the retort in a vertically, longitudinaldirection, it is pro posed to intervene either between the upper nonheated casing or the lower non-heated section represented by the cokereceptacle a loose joint of any desired construction.

The stoppers S at the upper ends of the gas tubes are fixed in place,thus preventing entrance of the material into the gas tubes orpassageways; but the gas exit ports 8 are continuously open so that thegenerated gas may continuously escape thcrethrough, into thecommunicating space above and then to the exit 9, while the retortingoperation is aclive.

The rocker shaft 6 mounted in openings of the wall of the receiver 5 forcoke or other residue of distillation, extends at both ends outwardly ofthe receiver. Each end has a dependent arm 6 for reception of one ormore removable weights 7, two of which are shown on each arm, Figs. 1,4, 5 and 10. The weights may be increased or diminished in numberaccording to the character of the material to be treated. Receiver 5 ispractically airtight but may be provided with an opening through whichthe residue of distillation may be removed from time to time, and theopening may be provided with a door, neither of which is shown.

The approximately fiat-sided screw casing having arcuate walls, betweeneach two flattened walls, is a feature of the invention. The arcuatewalls are closely adjacent and partially enclose opposed portions of thefood screw helices while the flattened sides, which are opposed to theoverlap or overhang of the helices, affords greater space for materialbeing fed than would be the case if the easings were of aeross-sectionally figure 8 contour.

The combustion chamber C is for heat applied during the retortingoperation which may be a low temperature operation for which theapparatus is especially intended.

The intake 10 is provided, in practice, with a gas-tight charging device10 of any desired construction. The charging device is herein indicateddiagrammatically.

In operation, succeeding initial charging, charge arresting andearbonization, the feed screws may be driven continuously and the chargearresting doors may be continuously opened for either partial momentaryinterrupt-ion of escape, or, for the continuous escape, of the coke intothe coke box, with the box door closed to prevent inrush of air, alldepending on the character of the material treated and the desire of theoperator.

The described arrangement for disposition of the descending material ina plurality of relatively small, cross-sectional and relatively thinwalled, lengthwise extending tubes and for simultaneous ascent ofevolved gas through the corresponding gas tubes,.insures a perfection ofcarbonization or distillation attended by maximum evolution by gas fromthe material.

Evolution and removal of the gas is continuous. The charging operationmay be continuous or intermittent depending on the type of chargingapparatus used. The discharge of the coke into the coke box isautomatically intermittent.

In Fig. 5, the gas escape 9 is shown discharging into a diagrammaticallyillustrated exhauster 9. The exhauster connection is sufficient inpractice to effect the ascent of gas into the escape 9, notwithstandingthe pressure on the charge between the feed screws and flap doors. Someof the ascending gas escapes from fissures in the coke and some of itfrom material M thereabove.

During the operation of a water gas generator, as is well understood,the generator is filled with carbonaceous material such as coke andraised to incandescence by means of an air blast, technically called theblow period. lVhen the proper degree of incandescence is reached, theblast or blow is shut off and steam is passed through the heatedmaterial, this operation being termed the run period. The interactionbetween the steam and the incandescent carbon generates the water gaswhich is a mixture composed principally of carbon monoxide and hydrogen.During the operation of manufacturing water gas, three sources of heatare developed apart from the heat which can be generated by burning thewater gas itself. These three sources of heat have heretoforeprincipally been regarded as waste heat and are as follows :(1) thesensible heat of the air blow gas; (2) the heat generated by thecombustion of the carbonmonoxide constituent of the blow gas, and (3)the sensible heat of the water gas, and

one of the objects of the present invention is to utilize the threeaforesaid sources of heat in connection with the distillation of solidcarbonaceous or other materials before they are allowed to pass to thechimney or stack. Experiments have shown that the heat generated orobtained from the three aforesaid sources is suflicient to effect thedistillation of carbonaceous materials. f

According to one feature of the present invention, the hot blow gas isconveyed from the water gas generator with as little less as possible ofits so-called sensible heat and together with a supply of preheated air,is ad-' mitted to a combustion chamber composed of refractory materialand which surrounds a retort within which a process of low or medium,distillation is to be carried on. A combustible mixture is thus producedwherein the sensible heat of the blow gas is added to the heat derivedfrom the combustion of the blow gas itself.

Another feature of this invention is to employ the hot water gas forsteam raising purposes or partial steam raising by passing the samethrough a heat interchanger, the heat generated in the heat interchangerbeing employed, for example, in raising the temperature of the watersupplied to the interchanger which water may be employed in an adjacentboiler, for raising steam and at the same time cooling the hot watergas.

As the process of producing blow gas and water gas is intermittent, twowater gas generators, may, if desired, be employed for alternate use.

During the blow period of gas generation and owing to the considerablepressure of the air employed for the blast or blow which air passesthrough the incandescent coke in the water gas generator a quantity ofhot ashes, cinders and dust are carried away with the blow gas andnormally are deposited in the neighborhood of the generator.Furthermore, the heat of the said ashes, representing about two per centof the heat of the coke with which the generator is fed is lost.

According to another feature of the present invention, and in caseswhere blow gas is ignited in a combustion chamber for the purpose oftreating carbonaceous or other materials, the blow gas, before enteringthe combustion chamber is passed through a soealled cyclone dustarrester. A suitable form of dust arrester consists of a cylindricalchamber with a conical lower part, the gases containing the cinders anddust being caused to enter the upper cylindrical part thereof at atangent to the periphery of the cylinder, whereby a whirling orcentrifugal'mos tion is imparted to the entering gases. Consequently thedust and cinders are thrown against the sides of the chamber and, bygravity, fall to the bottom thereof where they may pass through a pipeor passage into a water sealed tank from which they are raked out fromtime totime.

According to a further feature of the present invention, and in caseswhere it is desired to ignite and utilize the blow gas in the aforesaidmanner, use is made of the heat of the cinders and dust which pass intothe dust extractor to. preheat the air required for the purpose ofigniting the blow gas. To this end an air inlet pipe is provided whichextends axially through the cyclone dust extractor the said air pipebeing surrounded by a concentrically mounted pipe or casing throughwhich the blow gas, after the dust \and ashes have been separatedtherefrom passes either to the retort, the boiler or elsewhere. Owing tothis arrangement, and on account of the fact that the hot dust and ashesraisethe temperature of the parts of the dust extractor to aconsiderable extent, the temperatureof the air is also raised to aconsiderable extent, the heating operation being further assisted by thesensible heat of the blow gas which may flow along the exterior of theair pipe until both concentrically mounted pipes enter the combustionchamber of the retort or the like.

Referring to the plant structure (Figs. 10 and 11), 31 is a retort stackor snift valve structure, 32 a water gas generator, 33 a dust extractorand preheater, 34 the separated dust outlet of the dust extractor orseparator; 35 is an air blower,'36 a motor connected with the blower, 37the blower discharge pipe, 39 a blow gas duct, 40 a subsidiary airsupply duct, the blow gas duct and subsidiary air duct dischargingclosely adjacent into the combustion chamber C; 41 is the verticalconduit leg of an L-shaped conduit theunder end of which is open withinthe chamber of the (lust extractor or separator and the upper horizontalleg of which is entrant into the combustion chamber. The subsidiary'airpipe 40 extends from the blower discharge pipe 37 into the under portionof the dust separator 33, thence upwardly within and out of contact withthe dependent conduit leg 41 and thence horizontally into the combustionchamber, the upper conduit leg forming the air supply duct 40 closelyadja cent the closed blow gas duct 39. 42 is the steam run pipe for thewater gas generator, 43 the blow gas discharge pipe from the Water gasgenerator into the upper end of the dust extractor 33, pipe 43 enteringthe dust extractor, which is circular in crosssection, tangentially. 44is the Water gas escape pipe from the chamber into a heat interehanger45; 46 is a conduit leading from theheat interchanger for conveyance ofcooled water gas therefrom to the junction of the pipe 46 at 47 with thecoal gas escape pipe 48 that is in connection with the gas escape pipe 9of the retort apparatus. The dust extractor 33 has anunder end, verticaldust and cinder discharge into a water tank 49 or other suitablereceptacle.

Referring to Figs. 10 and 11 of the drawings, 31 is a chimney stackwhich in connection with a water gas plant is'termed snift valve. Duringthe so-called air blow period this is opened by a lever attached to achain; but during the steam run period, the valve is shut so as toretain the heat of the blow in the combustion chamber.

32 is the water gas generator of which any well-known type may beselected, the sequence of operations being practically the samewhichever type of water gas generator be employed.

The fuel required by the water gas generator, viz coke is preferablysupplied from the carbonizing retort to generator 32 which in turnsupplies the necessary heat to the retort to enable it to produce thenecessary coke, the relation between the two apparatus items being thusreciprocal.

The coke in the water gas generator is blown to incandescence by theturbine positive air blower 35 which is actuated by motor 36. Air passesto the water gas generator 32 by pipe 37 upwards through the coke chargein the generator, being in its passage converted by contact with the redhot carbon into so-called blow gases which are largely a mixture ofcarbon monoxide (CO), and carbon dioxide (CO and nitrogen (N These gasesbefore passing into the combustion chamber C surrounding the retortenter the dust extractor 33 wherein, by thecentrifugal action of theblast, the ashes, cinders and dust in the blow gases, representing sometwo per cent of the total heat of the fuel supplied to the generator,are absorbed; and the cleansed gases enter the port leading to thecombustion chamber through duct 39.

The blow gases would be unignitable unless. supplied with a sufficiencyof air, preferably heated, as the hotter this air supply is the moreeffective and intense is the combustion of the combustible CO in theblow gases. Consequently, a certain quantity of the air representing themain blow to the water gas generator is tapped off by a subsidiary pipe40 controlled by a valve, the pressure exerted by the turbine blower 35being sufficient to force this air supply through the pipe 41 whichpasses through the lower end of the gas outlet pipe 40 and extendsthrough the same. Both the main blow gas pipe 39 v and the smaller airpipe 40 are entrant into the combustion chamber together, where ignitiontakes place; the air having picked up the heat from the ashes, cindersand dust which are scattered allover the interior of the dust extractor.

Returning to the water gas generator, the blow period as described abovebeing finished, after say four minutes of air blow, the

ca of the chimney stack are closed. No ya ves are shown or described asthe working of the valves are well known and to explain in detail wellknown 0 erations would unnecessarlly complicate botli drawings andexplanation.

The blow valves being closed, the valves operating the run are 0 enedand steam is near 1100 Fah. The temperature of a very large volume ofthe produced water gas, is

such as to either raise some pounds of steam or to raise the temperatureof cold water to over the boiling point so that this water could be usedas feed water to an adjacent steam boiler.

It is necessary to cool the evolved, heated water gas to a normal atmosheric temperature before the same could e usefully employed.

Therefore, to accomplish both the cooling of the large quantity ofheated water gas and to usefully employ the sensible heat of the same,the heated water gas is passed by pipe 44 into a so-called interchanger45 which is fed by cold water which coming into contact with thesensible heat of the water gas, is raised to practically the sametemperature, allowance being made for radiated and converted heatlosses. But by a properly constructed heat interchanger, all thesensible heat can easily be removed from the heated water gas and asupply of low pressure steam or water heated to over 212 Fah. can beobtained.

On leaving the heat interchanger, the cooled water gas passes by pipe 46to the pipe junction 47 where it meets and ismixed with rich coal gasfrom the retort through the pipe 48 that communicates with the gasoutlet 9 of the retort.

In the distillation of coal, the products are a rich coal gas; ammoniavapors, tar oils containing spirits, oils, tar acids of the cresolphenoltypes, paraflin wax, and pitch containing a very low percentage of freecarbon and coke.

The quantity and quality of these products depends entirely on thetemperature at which the fuel selected is carbonized in the specialretort and one object of the process is to effect carbonization at atemperature which will yield a very rich gas of about 600-800 B. t. u.per cubic foot and which will produce oil-bearing vapors which, on beingcondensed, will be of the aliphatic series of parafiinoids and removedas far as possible from the arcvalves controlling the blow and likewisethe matic or benzenoid series, and to effect this stand say 1700 Fah.the objectionable naph result the temperature within the carbonizing anddistillation retort itself must not exceed or considerably exceed some Il-00 Fah. as be end this temperature the benzenoid seriesbegin toappear, and if the temperature be raised to a maximum the retorts couldthalene series would likewise appear.

The dust laden blow gas enters the dust separator through its circular,casing side and discharging interiorly to some extent tangens tiallycauses the dust laden gas to whirl violently as indicated by arrows, thedust and cinders dropping downwardly through the under outlet 34 into awater tank.

The coal becomes plastic in a stratum or in strata where it changes intocoke in the retort. By keeping the in-fed coal and the coking plasticstratum or strata under constant pressure as olescribed,'the formationof thin and fragile walled coke cells is revented and a dense com actcoke pro not obtained. Such a densi cation is of very great importanceto the coke product as it does not break up or give oflf coke dust as isthe case with coarsely cellular coke. Moreover, the constant compressionis favorable to evolution of the gas evolving .from the coking portionof the coal and from the coal.

tical carbonizing retort; carbonizing the coal under mechanical pressureto produce coalgas and coke; separately removing the coal-- gas from theretort; passing the coke into a water-gas generator; air blasting thecoke in the water gas generator and thereby generating blow-gas; passingthe blow-gas in heat interchange with air; mixing the blow-gas andheated air; burning the mixture and thereby externally heating thecarbonizing retort; then alternately passing steam downwardly throughthe heated coke in the watergas generator and thereby generatingwatergas; separately removing the hot water gas from the water-gasgenerator; cooling the water-gas by heat interchange with water in asteam boiler and thereby generating steam for the water-gas generatlon;and then mixing the water-gas with the coal-gas, substantially asdescribed,

Signed at New York city, in the county of New York and State of NewYork, this 12th day of March A. D. 1926.

FREDERICK BEACON MARSHALL

